In the past, anchors have employed the concept of snapping-in and have required a twisting motion of approximately 10 or 12 revolutions for release. Typical of such designs are the Model K and Model KC anchor tubing seal nipples produced by Baker Oil Tools and used in permanent packer systems. While this design has functioned adequately in many applications, there are several limitations of this prior known design. One of these limitations becomes significantly more pronounced in deep wells where the length of the tubing string is necessarily significantly longer than shallower wells. In the deeper wells, it becomes difficult to apply enough torque at the surface so that the sufficient releasing torque is applied at the engagement of the anchor so that it will release. The reason for this is that due to the flexibility of the string in a torsional mode, some of the torque applied at the surface is not directly transmitted to a twisting moment at the anchor. Additionally, on deviated wells, it becomes more problematic to apply significant torques to the tubing string because of the potential for damage to the tubing string by interference against the wellbore or a casing.
Another problem experienced by operators when using anchors of known design is the prior designs did not allow initial engagement into the packer body with a possibility to disengage before passing the point of no return which required breaking shear screws which then in turn required a trip out of the well to reset the tool. The problem occurs when the engagement into the packer body occurs at a point in time where there is not a sufficient amount of tubing extending above the rig floor to position the tubing hangers; yet, further downward movement is required to set the anchor.
The apparatus of the present invention addresses this concern by allowing the operator to disengage, even after initial contact with the packer so that an additional pup joint can installed at the surface to leave sufficient room to place the tubing hangers at the surface and to allow further downward movement necessary to latch the apparatus. Additionally, the apparatus of the present invention is disengageable by an upward pull and requires no twist.